1. Field of the Invention
The present invention relates to a printing element for a rotary printing machine which is equipped with a plurality of carriages, each carriage receiving an impression cylinder.
2. Description of the Related Art
It is known that the aim, even in rotary printing machines, is to avoid the dead times which occur, for example, as a result of a machine standstill during an operation to exchange the receiving carriages for the impression cylinders in the course of a change in production.
If it is assumed that the size of run in printed products produced in a rotary printing machine tends to become smaller in each run, it becomes clear that frequent interruptions in the production of the rotary printing machine in order to exchange the cylinder-receiving carriages, the inking device and the impression cylinder lead to a substantial increase in the machine standstill times. An average person skilled in the art also knows that additional work operations, to be seen, for example, in a stopping of the paper web or a raising of the pressure roller, have to be carried out in order to exchange a receiving carriage for the impression cylinder. The function of the pressure roller is to press the paper web, during the printing operation, against the cylinder provided with a printing plate.
Subsequent to the execution of these and other additional work operations, it will become possible to extract the carriage receiving the impression cylinder from the associated printing element, in order thereafter to introduce a new carriage together with a new impression cylinder.
Furthermore, it is necessary beforehand to prepare the receiving carriage for the printing operations to be carried out and, after the introduction of the carriage, to run the new impression cylinder up to the desired working speed, in order thereafter to bring about a lowering of the pressure roller so as to press the moving paper web onto the new impression cylinder and initiate a printing operation for a new run.
In order to carry out all the above-described operations for a plurality of printing elements when the run is changed, it is necessary, in practice, to stop the entire rotary printing machine, thus leading to a stand-still time of the printing machine for a relatively long period, as a result of which the efficiency of the printing machine drops considerably.